SEGMENT DATA (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014 Segment	Mar. 31, 2013	Dec. 31, 2013
SEGMENT DATA [Abstract]
Number of Reportable Segments	2
Revenues [Abstract]
Marine transportation	$ 435,771	$ 418,518
Diesel engine services	153,475	140,267
Total revenues	589,246	558,785
Segment profit (loss)	101,000	91,936
Total assets	3,805,704		3,682,517
Other segment disclosures [Abstract]
Gain (loss) on disposition of assets	51	(32)
Interest expense	(5,618)	(7,988)
Other income (expense)	(236)	75
Details of "Other" total assets [Abstract]
Total assets	3,805,704		3,682,517
Marine transportation [Member]
Revenues [Abstract]
Segment profit (loss)	97,551	89,253
Total assets	3,165,657		3,046,692
Details of "Other" total assets [Abstract]
Total assets	3,165,657		3,046,692
Diesel engine services [Member]
Revenues [Abstract]
Segment profit (loss)	12,772	14,022
Total assets	572,709		576,472
Details of "Other" total assets [Abstract]
Total assets	572,709		576,472
Other [Member]
Revenues [Abstract]
Segment profit (loss)	(9,323)	(11,339)
Total assets	67,338		59,353
Other segment disclosures [Abstract]
General corporate expenses	(3,520)	(3,394)
Gain (loss) on disposition of assets	51	(32)
Interest expense	(5,618)	(7,988)
Other income (expense)	(236)	75
Profit (loss) from other segment	(9,323)	(11,339)
Details of "Other" total assets [Abstract]
General corporate assets	65,095		57,197
Investment in affiliates	2,243		2,156
Total assets	$ 67,338		$ 59,353